Dietetics, Nutrition and Biological Sciences
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Item Effects of oat β-glucan consumption at breakfast on ad libitum eating, appetite, glycemia, insulinemia and GLP-1 concentrations in healthy subjects.(2018-06-18) Zaremba, Suzanne; Gow, Iain F.; Drummond, Sandra; McCluskey, Jane T.; Steinert, Robert E.There is evidence that oat β-glucan lowers appetite and ad libitum eating; however, not all studies are consistent, and the underpinning mechanisms are not entirely understood. We investigated the effects of 4 g high molecular weight (MW) oat β-glucan on ad libitum eating, subjective appetite, glycemia, insulinemia and plasma GLP-1 responses in 33 normal-weight subjects (22 female/11 male, mean age (y): 26.9 ± 1.0, BMI (kg/m ): 23.5 ± 0.4). The study followed a randomised double-blind, cross-over design with subjects fed two test breakfasts with and without oat β-glucan followed by an ad libitum test meal on two different days. Blood samples and ratings for subjective appetite were collected postprandially at regular time intervals. Oat β-glucan increased feelings of fullness (p = 0.048) and satiety (p = 0.034), but did not affect energy and amount eaten at the ad libitum test meal. There was a treatment by time interaction for plasma GLP-1, plasma insulin and blood glucose. GLP-1 was significantly reduced at 90 min (p = 0.021), blood glucose at 30 min (p = 0.008) and plasma insulin at 30 and 60 min (p = 0.002 and 0.017, respectively) following the oat β-glucan breakfast when compared with the control breakfast. Four grams of high MW oat β-glucan lowers appetite but not ad libitum eating and beneficially modulates postprandial glycaemia, it does however, not increase plasma GLP-1 secretion. [Abstract copyright: Copyright © 2018 Elsevier Ltd. All rights reserved.]Item Pharmacological & Physiological Characterisation of the Rat Mammary Artery at Different Stages of Reproduction: Final Report to the Scottish Government Rural and Environment Research and Analysis Directorate (RERAD).(Scottish Government, 2009) Gow, Iain F.The overarching-aim of the project was to assess the responsiveness of the rat mammary artery during different stages of the reproductive cycle. This has implications for not only normal physiology, but also heart disease, since women who undergo coronary artery bypass surgery using mammary arteries as the conduit and who have breastfed their offspring have a significantly better prognosis that those who have never breastfed.Item Post-prandial effects of a meal rich in long-chain omega-3 fatty acids on indicators of cardiovascular risk(2012) McKenzie, Jane; Gow, Iain F.; Findlay, S.; Petit, J.; Goua, M.; Wainwright, C.; Davidson, IsobelIntroduction Evidence from epidemiological studies indicates that the regular consumption of oily fish may be protective against the risk of cardiovascular disease. The benefits appear to be related to the content of long-chain omega-3 fatty acids (LC n-3 PUFA), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Current UK dietary guidelines therefore recommend the consumption of two portions of fish per week, one of which should be oily (1), which equates to 0.45g LC n-3 PUFA per day. Although there is limited information about intakes of EPA and DHA in Scotland, recent studies show that they are consistently below recommendations (2). Further review of the dietary intake data indicates that the consumption of oily fish is sporadic and inconsistent (3) despite attempts to promote regular intake. Several of the mechanisms involved in the development of cardiovascular disease (CVD) involve endothelial function. Post-prandial hyperlipidaemia has been linked to an increased risk of CVD (4), which is largely attributed to the transient (2-6 hour) decrease in endothelial function (5). Changes in endothelial function have also been shown to be associated with superoxide production (6), implicating oxidative stress as a possible mechanism for endothelial dysfunction. The long-term effects of LC n-3 PUFA on oxidative stress and inflammation are well established, however little is known about their immediate post-prandial effects. Identifying the possible benefits of consumption of a single meal rich in LC n-3 PUFA may provide a new perspective on which to promote dietary changes. The aim of this pilot project was therefore to identify post-prandial changes in markers of cardiovascular risk, assessed by measurement of arterial compliance, whole blood fatty acid profile, plasma glucose and insulin, markers of endothelial dysfunction, oxidative stress and antioxidant status in response a test meal naturally rich LC n-3 PUFA compared with a control meal.Item Effect of Oatmeal on Postprandial Vascular Compliance Following a High Fat Meal(IMedPub, 2016-02-12) Devlin, N.; McKenzie, Jane; Gow, Iain F.Background and aim: Postprandial hyperlipidaemia has been associated with acute cardiovascular effects e.g. endothelial dysfunction and peripheral vasodilatation. Oats have known health benefits, and may reduce the transient, post-prandial endothelial dysfunction. The aim of this short study was to investigate if markers of endothelial function pulse wave velocity (PWV) and augmentation index corrected for heart rate (AIx@75) are affected by a meal with varying levels of saturated fat, with or without oatmeal. Methods and results: Fourteen subjects (aged between 22 and 51 years) were recruited. On their first visit, following baseline measurements of anthropometry, blood pressure (BP), heart rate (HR), PWV and AIx@75, they were given one of three meals (low fat, high fat, and high fat with 60g oatmeal) in a randomised order. Subjects returned three hours later for re-assessment of BP, PWV and AIx@75. Visits two and three followed the same protocol, but only BP, HR, PWV and AIx@75 were measured. There was a significant correlation between baseline PWV and systolic pressure (p<0.02), and AIx@75 and diastolic pressure (p<0.005). AIx@75 was positively related to BMI and waist circumference (p<0.01 and p<0.005 respectively). AIx@75 fell following the high fat meal (p<0.05), but not when oats were taken. Heart rate increased following the high fat meal with oats (p<0.05), but no differences were found between fasting and postprandial PWV after any of the meals. Conclusion: AIx@75 was correlated with BMI and waist circumference. The decrease in AIx@75 following the high fat meal requires further investigation, and AIx@75 is possibly a more sensitive marker of arterial compliance than PWV in a young healthy population.Item An investigation of the post-prandial effects of a meal rich in long-chain omega-3 fatty acids(2012) McKenzie, Jane; Paterson, E.; Bell, G.; Gow, Iain F.Item The life and death of breast cancer cells: proposing a role for the effects of oestrogen and phytoestrogens on potassium channels(Springer, 2011-07-15) Wallace, J.; Gow, Iain F.; Warnock, Mary; QMU BursaryChanges in the regulation of potassium channels are increasingly implicated in the altered activity of breast cancer cells. Increased or reduced expression of a number of K+ channels have been identified in numerous breast cancer cell lines and cancerous tissue biopsy samples, compared to normal tissue, and are associated with tumor formation and spread, enhanced levels of proliferation, and resistance to apoptotic stimuli. Through knockout or silencing of K+ channel genes, and use of specific or more broad pharmacologic K+ channel blockers, the growth of numerous cell lines, including breast cancer cells, has been modified. In this manner it has been proposed that in MCF7 breast cancer cells proliferation appears to be regulated by the activity of a number of K+ channels, including the Ca2+ activated K+ channels, and the voltage-gated K+ channels hEAG and Kv1.1. The effect of phytoestrogens on K+ channels has not been extensively studied but yields some interesting results. In a number of cell lines the phytoestrogen genistein inhibits K+ current through several channels including Kv1.3 and hERG. Where it has been used, structurally similar daidzein has little or no effect on K+ channel activity. Since many K+ channels have roles in proliferation and apoptosis in breast cancer cells, the impact of K+ channel regulation by phytoestrogens is of potentially great relevance.Item Infusion of Mg in Humans Acutely Reduces Serum Insulin Levels: a Pilot Study(John Libbey Eurotext, 2011-12) Gow, Iain F.; O'Donnell, M.; O'Donnell, L.; Flapan, A.Background: infusion of Mg for therapeutic purposes is still a matter for debate. Dosages vary considerably, yet subclinical effects on normal physiology are largely ignored. In human and animal models, interactions between Mg and insulin exist, thus we have investigated the effect of infusing Mg on serum insulin, ionised Mg (Mg2+) and Ca (Ca2+) and plasma glucose in human volunteers. Methods: six male volunteers were infused with magnesium sulphate (MgSO4) dissolved in normal saline, using a high-dose loading- bolus, followed by a lower-level maintenance- period. Findings: serum Mg2+ rose rapidly throughout the bolus infusion, declined during the maintenance phase, but remained higher than pre-infusion levels throughout the experimental period; serum Ca2+ rose when serum Mg2+ was highest. Infusion of MgSO4 had no effect on heart rate or blood pressure, but caused a rapid, pronounced drop in circulating fasting insulin (p < 0.0005), which slowly recovered to basal values during the course of the maintenance infusion. A slight, transient rise in plasma glucose (p < 0.05) concomitant with the decline in serum insulin was also observed. Interpretation: it is possible that the effect of Mg2+ on insulin may have been due to antagonism of Ca2+ entry in pancreatic beta-cells, the insulin decline causing a subsequent rise in circulating glucose levels. We suggest that these effects of MgSO4 infusions should be considered where the aim is to achieve high doses of blood Mg2+ levels by clinical intervention.